/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.table.operations.utils;

import org.apache.flink.annotation.Internal;
import org.apache.flink.table.api.ValidationException;
import org.apache.flink.table.catalog.ContextResolvedFunction;
import org.apache.flink.table.catalog.ResolvedSchema;
import org.apache.flink.table.expressions.CallExpression;
import org.apache.flink.table.expressions.ResolvedExpression;
import org.apache.flink.table.functions.FunctionKind;
import org.apache.flink.table.operations.FunctionQueryOperation;
import org.apache.flink.table.operations.QueryOperation;
import org.apache.flink.table.types.DataType;

import static org.apache.flink.table.expressions.ApiExpressionUtils.isFunctionOfKind;

/** Utility class for creating a valid {@link FunctionQueryOperation} operation. */
@Internal
final class FunctionTableFactory {

    QueryOperation create(ResolvedExpression resolvedCall) {
        if (!isFunctionOfKind(resolvedCall, FunctionKind.PROCESS_TABLE)) {
            throw new ValidationException(
                    "Invalid expression. The expression must be a call to a process table function.");
        }
        final CallExpression call = (CallExpression) resolvedCall;
        final ContextResolvedFunction contextFunction =
                ContextResolvedFunction.fromCallExpression(call);
        final DataType dataType = call.getOutputDataType();
        return new FunctionQueryOperation(
                contextFunction,
                call.getResolvedChildren(),
                ResolvedSchema.physical(
                        DataType.getFieldNames(dataType), DataType.getFieldDataTypes(dataType)));
    }
}
